Wideband receivers may be configured to have an antenna connected directly to down-conversion mixers (e.g., a mixer-first receiver). The receiver can employ passive mixers, in which the passive mixers immediately down-convert the input current to baseband. A transimpedance amplifier (TIA) then converts current in the receive band to voltage. In this regard, a received signal may include an unwanted blocker signal at frequency fb, and a wanted signal at frequency fw, which may be Δfb greater than fb, e.g., fw=fb+Δfb.
Passive-mixer based receivers can be configured to provide sharp filtering to most out-of-band blockers before baseband amplification. However, the output of the TIA may have a signal located at harmonics of the wanted signal that experiences some amplification. Although the bandwidth around these harmonics can be very small, blocker signals located at these precise harmonic frequencies potentially cause the amplified signal to clip. For example, a receiver gain of 20× could potentially amplify a 1V blocker signal to 20V. This unnecessary amplification of such blocker signals has potential to saturate the receiver, thus resulting in degradation of performance.